1. Field of the Invention
This invention relates broadly to non-aerosol sprayers. More particularly, this invention relates to a sustained duration mechanical sprayer.
2. State of the Art
Many household and industrial products are sold in containers that include a sprayer. These products include cleansers, insecticides, polishes, waxes, etc. There are several kinds of sprayers used with these products. Perhaps the most common is the manual push button or trigger operated pump which is seen most frequently on liquid cleansers. It has the advantage of being environmentally friendly (i.e. it does not require a propellant) but the disadvantage of delivering fluid in a series of pulses rather than in a continuous spray. Another well known sprayer is the aerosol can which is sealed and charged with a gas propellant. This sprayer has the advantage that it dispenses fluid in a continuous spray, but has several disadvantages. One disadvantage is that the can cannot be refilled. Another disadvantage is that depending on the gas used to charge the container, the propellant can be environmentally unfriendly. While environmentally friendly propellants do exist, generally, they do not charge as well as the unfriendly gases. Still another popular sprayer is the air pump sprayer seen most frequently with insecticides and liquid garden products. See, for example, U.S. Pat. No. 4,192,464 to Chow. The pump sprayer includes a hand operated air pump which is used to charge the container with compressed air. After it is charged, it operates much like an aerosol can except that the spray head is typically attached to the container by a hose and the container is supplied with a carrying handle. The design permits a gardener to charge the pump while it is on the ground, then carry it in one hand with the handle while the other hand operates the sprayer. The air pump sprayer is environmentally friendly but requires considerable effort to keep charged because air is not as efficient a propellant as environmentally unfriendly gases such as FREON or hydrocarbon gasses. Charging requires that the container be placed on the ground while the gardener pumps the air pump.
Still another type of sprayer is the spring biased sustained duration pump. An example of such a pump is shown in U.S. Pat. No. 5,810,211 to Shanklin et al. Like the air pump described above, these sprayers are typically used for garden products such as insecticides, herbicides, etc. The pump is mounted inside the fluid container and is coupled to a hand held sprayer by a hose (flexible tube). The container is provided with a handle and the pump is primed while holding the container on the ground or on a surface like a table top. The spring biased pump does not utilize air to propel liquid from the container through the nozzle. Rather, a spring biased piston is provided inside a cylinder and connected to a rod which extends through the spring, out of the cylinder and out of the container terminating with a handle. A one-way inlet valve is coupled to the cylinder and the tube from the spray head is coupled to the cylinder via a one-way outlet valve. When the handle is pulled, the piston is moved through the cylinder against the spring, drawing liquid from the container into the cylinder via the one-way inlet valve. When the handle is let go, the spring exerts force against the piston which pressurizes the liquid in the cylinder. The only outlet for the liquid is through the one-way outlet valve into the tube to the spray head which has a spray valve to control dispensing of the liquid. When the spray valve is opened by pushing a button on the hand held sprayer, liquid under pressure flows from the cylinder through the tube to the spray valve, through the spray valve and out a nozzle on the hand held sprayer. The duration of the spray depends on the volume of the cylinder, the force of the spring, and the size/shape of the nozzle. When the spring returns the piston to the starting position, the sustained continuous spray ceases and the pump must be primed again. The amount of liquid in the cylinder can be gauged by the length of the rod extending out of the container.
The spring biased sustained duration pump has many advantages. It is environmentally friendly. It is relatively easy to operate and it is potentially more efficient than the air pump sprayer. However, these sprayers also have some disadvantages. The fact that the container must be held down with one hand while the pump is primed with the other hand is a disadvantage. The fact that the pump cylinder occupies space inside the fluid container is another disadvantage. It is also a disadvantage that the piston rod extends out of the liquid container when the pump is primed. This projecting rod is awkward and can get in the way or get caught on something as the sprayer and container are carried about in use.
Some of the aforementioned disadvantages have been addressed in U.S. Pat. No. 6,415,956 to Havlovitz which proposes locating the spring biased piston and cylinder in the hand held sprayer. However, this does not cure the awkwardness of the piston rod extending into space where it can get in the way or get caught on something. Moreover, in order to accommodate the pump in the hand held sprayer, a rather complex spray valve arrangement is required.